Cathode ray deflection apparatus



om., 2'?, w42 I, WOLFF 30am CATHODE RAY DEFLECTION APPARATUS Filed April 26,1939

51m/700w WA? VE f5/mmm@ Bnnentor Patented Cct. 27, 1.942

CATHODE BAY DEFLECTION APPARATUS Irving WoliI, Merchantville, N. J., asslgnor to Radio Corporation of America, a corporation of Delaware Application April 26, 1939, Serial No. 270,123

f (Cl. Z50-27) Claims.

This invention relates to cathode ray deflection apparatus and more particularly to a deflection means which may be used to expand or accelerate any portion of the scale.

In cathode ray deflection devices the timing deflections have been made both linear and nonlinear. One well known deflection is obtained by applying potentials of sine wave form to the deilecting elements. The saw-tooth scanning is another well known deiiection means for cathode ray tubes.

One of the applications of cathode ray tubes is for pulse echo detection. 'Ihe pulse is radiated toward a reflecting object; the cathode ray is deected by a scanning potential of suitable wave form; and the reflected wave is applied to deiiect the cathode ray along a coordinate angularly disposed with respect to the scanning coordinate. If the scanning is synchronized with the outgoing pulses and if the scanning is at a known rate, the distance from the transmitter to the reflecting object and back to the receiver may be determined. In this type of scanning more than one reilection may be indicated, and in many instances it is desirable todiierentiate the several reectons. If the several reflections are uniformly spaced along the entire scanning scale, there is no difficulty in determining the distances on a linear scale. If the reections are closely grouped in any portion of a linear or hyperbolic scale, it becomes diflicult to distinguish the separate reflections.

One obvious solution of this difficulty is to employ several diiierent scales and to use the scale best suited, This solution complicates the apparatus and does not lreadily solve all the difficulties. One of the objects of this invention is to provide means whereby any portion of a cathode ray scanning or timing scale may be expanded. Another object is to provide means for obtaining very sensitive diilierential indications of the distance of reflecting objects. An additional object is in the provision of means for exaggerating any portion of a linear or non-linear cathode ray sweep.

The invention will be described by reference to the accompanying drawing in which Figure 1 is a schematic circuit diagram of one embodiment' of the invention; and Figures 2 to 4 are graphs descriptive of the operation of the device.

Referring to Fig. 1, the output of\a saw-tooth wave generator is connected to a pair of potentiometers 3, 5. ilrst potentiometer 3 is connected through a capacitor 1 to the grid of an amplier 9. The grid The adjustable contact of the is returned to ground by a resistor I I. The cathode lead may include a self-bias resistor I3. The

anode is connected through a resistor I5 to a potentiometer I1 which is connected to +B as hereinafter described. The anode is coupled by a capacitor I9 to an output resistor 2| which is shunted across the deecting elements 23 of a cathode ray tube 25.

The adjustable contact of the second potentiometer 5 is connected through a capacitor 21 to the grid of a preferably high mu type of thermionic tube 29. The grid is connected through a resistor 3| to an adjustable contact on the biasing potentiometer 33 in the cathode of the tube 29. Theanode of the tube 29 is connected to the upper terminal of the potentiometer I1. lower terminal of the potentiometer |1 is coupled by a capacitor 35 to the output resistor 2 I.

The operation of the circuit is as follows: 'Ihe potentials of saw-tooth wave form applied to the ilrst potentiometer 3 are amplied by the ampliiler 9 which is biased for normal operation. The amplified output currents may be linear as shown by the straight line 31 of Fig. 2 or the tube may be adjusted to the output characteristic represented by the curve 39. is biased to cut-oi. The anode current remains blocked for the lower potentials of the input voltage of saw-tooth wave form as shown by the left hand portion of Fig. 3. As the input potential is increased the initial bias is exceeded and the output current 4| rises steeply. A further increase of input is finally accompanied by grid current which, flowing through the series resistor 3|, limits the anode current 43.

The voltage drops across resistors I5 and |1 are combined in resistor 2| and are applied to the deflecting elements 23 of the cathode ray tube. The resulting combination for linear scanning is represented by the graph 45 of Fig. 4. If the expanded scanning voltage is combined with the non-'linear scanning voltage, the resultant is represented by the dash line 41. It should be understood that the expanded or modif-led portion may be applied at any point along the horizontal coordinate, which may represent voltage, time or distance in suitable units.

Thus the invention has been described as an improved cathode ray deecting device in which the normal linear or non-linear scanning may be expanded in any portion of the scale. The control is accomplished by an auxiliary tube which is lyreaches saturation. This characteristic cur- The The high mu tube 29 n 'rent is added to the normal scanning current. While triode tubes -have been shown for purposes of illustration, it should be understood that tetrodes or other types of amplifiers may be used.

I claim as my invention:

1. A cathode ray sweep circuit including a source of sweep potential of saw-tooth wave form, an ampliiler having an input and an output circuit, means i'or applying said sweep potential to said input circuit, a second ampliiler having an input and an output circuit and an operational characteristic diiierent from said iirst mentioned amplifier, means for applying said sweep potential to the input o! said second amplier, means for biasing said second amplilier to cut-off in the absence of said sweep potential, and means for adding the output of one of said amplifiers to any portion intermediate the minimum and maximum output of the other of said ampliiiers to obtain a sweep potential in which the sweep rate is diierent at dierent 'portions of the sweep.

2. A cathode ray sweep circuit including a source of sweep potential o1' saw-tooth wave form, an amplifier having an input and an outputvcircuit. means for applying said sweep potenl'tial to said input circuit a second Lampliiier having an input and an output circuit, said second amplier having an operational characteristic different from said first named amplifier, means for applying said sweep potential to the input of said second ampliiier, means i'or biasing said second ampliiier to cut-oil' in the absence oi' said sweep potential, means for limiting the gain oi said second ampliiier, and means for combining the outputs of both of said amplifiers.

3. A timing circuit including a source of potential of saw-tooth wave form, an amplifier having 'an input and an output circuit, means for applying said potential to said input circuit, a second amplifier having an input and an output circuit, said "second amplifier havingy an operational characteristic different from said iirst named amplifier, means for applying said potential to the input oi' said second amplier, means for biasing said second ampliiier to cut-off in theabsence of said potential of saw-tooth wave form, and means for combining the output oi' oneof said amplifiers with anyportion inter, mediate the minimum and maximum output of the other of said amplifiers to obtain a potential of saw-tooth wave formI in whichv at least two slopes appear in each timing wave.

4. A timing circuit including a source of potential of saw-tooth Wave form, an amplier having an input and an output circuit, means for applying said potential to said input circuit, a second ampliiier having an input and an output circuit, said second amplifier having an operating characteristic differing from said iirst-mentioned amplifier, means for applying said potential to the input oi' said second amplier, meansv for biasing said second ampliiier to cut-off in the absence of .said potentials of sawtooth wave form, means for limiting the'gain of said second ampliiier, and means for combining the outputs of both of said amplifiers.

5. A timing circuit for a cathode ray tube including a source of sweep potential, a iirst ampliiier having an input and an output circuit, means for 'applying said sweep potential to said input circuit, a second amplifier having a different operational characteristic than said rst amplifier and having an input circuit and an' output circuit, means for applying 4said sweep potential to the input circuit of said second amplier, means for biasing said second ampliiler to cut-oi! in the absence of said sweep potential, and meansv for combining the output of said second ampliner with the output o! said iirst amplifier at any portion intermediate the minimum and maximum output oi' said iirst ampliiier soV that the wave form `of the combined outputs includes at least tlvo rates of change for each timing sweep.

6. A timing circuit for a cathode ray tube including a source of sweep potential, a nrst amplifler having an input and an output circuit, means for applying said sweep potential to said input circuit,-a second amplifier having a diiler- 'ent operational characteristic than said first ampliner and having an input circuit and an output circuit, means for. applying said sweep potential to the input circuit oi' said second ampliiier, means for biasing said second ampliner to cut-oil in the absence of said sweep potential, means for limiting the gain of said second amplifler, and means ior combining the outputs of both of said amplifiers.

'7. A timing circuit including a source of varying potential, a first am'pliiier having an input and an output circuit, means for selecting and applying a portion of. said varying potentialto said input circuit, a. second amplier having a dierent operational characteristic than said first amplifier and having an input circuit and an output circuit, means for applying said varying potential to the input circuit ofsaid second amplifier, means for biasing said second amplifier to cut-ofi in the absence of said varying potential, and meansfor adding the output of said second ampliiier to any portion intermediate the minimum and maximum output of said first ampliiier so that the combined output varies at diilerent and predetermined rates at predetermined portions of said varying potential.

8. A timing circuit including a source of varying potential, a iirst ampliiier having an input and an output circuit, means for selecting and applying a portion oi' said varying potential to said input circuit, a second amplifier having a diilerent operational characteristic than said ilrst ampliiier and -having an input circuit and an output circuit, means for applying said varying potential to the input circuit of said second amplifier, means for biasing said second amplifier to cut-oil' in the absence of said sweep potential, means for limiting the gain of said second amplifier, and means for combining the outputs of both oi* said amplifiers.

9. A timing circuit including a. source of varying potential, a first amplifier having an input and an output circuit, means for selecting and applying a portion of said varyingv potential to said input circuit, a second ampliiier having a different operational characteristic than said first amplifier and having an input circuit and an output circuit, means for selecting and applying a portion of said varying potential to the input circuit of said second amplier, means for biasing said second amplifier to cut-on in the absence cil said varying potential, and means for adding the output of said second ampliiier to any desired portion intermediate the minimum and maximum output oi said iirst ampliler so that saidoutput varies as a function oi time at at least two diilerent rates foreach variation of potential of said source.A

10. A timing circuit including a source of vary- .ing potential, a iirst amplifier having an input and an output circuit, means for selecting and applying a. portion of said'varying potential to said input circuit, a second ampliiier having a. different operational characteristic than said first ampliiier and having an input circuit and an output circuit, means for selecting and ap- Flying a portion oi.' said varying potential to the input circuit oi said second ampliiier, means for biasing said second amplifier to cut-oi! in the absence oi said sweep potential, means for limit- 1 ing the gain of said second amplifier. and means for combining theoutputs oi both oi said ampiiiiers.

` IRVING WOII?. 

